The present invention relates to a folded plastic bag, a roll of folded plastic bags, and a bag dispensing system employing the roll of folded plastic bags in a dispenser.
In recent years, various systems for dispensing bags have been developed, these systems providing a mechanism for dispensing bags from a roll of continuous bags separated from one another by a line comprising perforations and a slit. The dispensing system employs a tongue to assist a user in separating the bag to be dispensed from the next bag on the roll, i.e., the adjacent upstream bag. More particularly, when the roll of continuous bags is unrolled so that a slit between two bags snags on the upstanding tongue member, the user continues to pull, causing the downstream bag to be separated from the adjacent upstream bag by tearing across the line of perforations until the bags are completely separated.
The bags used in such bag dispensing systems have been bags having star seals and eight contiguous plies, with a slit through all eight contiguous plies. These bags are somewhat difficult to open because the device which cuts the perforations and slits tends to cause xe2x80x9cmicro weldingxe2x80x9d of the contiguous plies to one another. The difficulty in opening the bags is also due to the narrow width of the bags. Various means to improve the opening of the star seal bags have been devised. However, these methods have involved some form of treatment of the perforations and slit, or treatment of the film from which the star sealed bag is made.
This invention provides a bag which is easier to open because it has folds along each edge which can readily be unfolded upon dispensing of the bag. As a result, opening the bag requires separation of only half of the number of plies of the star seal bag of the prior art. In addition, the manner in which the bag is folded allows the bag to be sealed so that the seal has a strength comparable to a star seal. Moreover, the folded bag can be rolled onto a core, with the resulting roll of bags having a width suitable for plastic bag dispensers in current commercial use.
As a first aspect, the present invention is directed to a bag dispensing system comprising a roll of plastic bags and a dispenser. The roll of plastic bags comprises a continuous web of folded, lay-flat, end-seal bags separated by a perforated separation line including a slit. The bags further comprise: (i) first, second, and third longitudinal folds which form a first gusset; (ii) fourth, fifth and sixth longitudinal folds which form a second gusset; (iii) a seventh longitudinal fold which is on a first half of the bag which contains the first, second, and third folds, the seventh fold forming a first folded bag flap; (iv) an eighth longitudinal fold which is on a second half of the bag which contains the fourth, fifth, and sixth folds, the eighth fold forming a second folded bag flap. Each bag is folded into a total of at least eight contiguous plies, with the slit being through all of the plies, or through less than all of the plies.
The dispenser comprises: (i) a support member for attachment to a support surface; (ii) a pair of guide channels carried by the support member for rotatably supporting the roll of plastic bags for rotation of the roll on the core and having an open end for receiving said core; (iii) a tongue spaced apart from and carried by said support member in a predetermined position corresponding to the predetermined position of the slit in the tear line. The roll of plastic bags is in direct contact with the dispenser at a braking point on the dispenser, with the roll of bags being positioned in the dispenser so that upon pulling a bag to be separated, the slit catches on the tongue, with further pulling causing the bag to be separated to tear free of the adjacent bag. Preferably, the bags are rolled so that the flaps are positioned inward of a remainder of the bag, i.e., positioned toward the axle upon which the bags are rolled. Preferably, the bags are symmetrically folded.
In this dispensing system, the plastic bags are wound on a core (i.e., an axle). The core having end portions which extend from the roll of bags, with the dispenser further comprising a pair of guide channels carried by the support member for rotatably supporting the roll of plastic bags for rotation of the roll on the core, the guide channels having open ends for receiving the extending end sections of the core. The guide channels hold the extending portions of the core for rotational and translational movement therewithin as the bags are individually dispensed from the roll. The roll of plastic bags is in direct contact with the dispenser at a braking region on the dispenser, to prevent an undesirable degree of freewheeling of the roll of bags during and after dispensing.
Alternatively, the invention is useful on other types of dispensers as referred to herein. As such, the roll of plastic bags can be coreless, have a solid core with ends which either extend from the planar sides of the roll of bags or which are flush with the planar sides of the roll of bags. If coreless, the roll of bags can be solid (i.e., without a hollow center), or can have a hollow center useful for hanging the roll on a dispenser.
As to the roll of bags, preferably the bags are interconnected as a strand, with successive bags being connected to one another via a line of perforations and a slit. Preferably, the slit is centrally-located. Preferably, the separation line further comprises perforations, i.e., in addition to the slit. The slit can be through just two plies, through four plies, or even through eight plies. The slit can be transverse, i.e., across the length of the bag, or can be parallel to the side edges of the bag, i.e., along the length of the bag. Preferably, the gussets do not contact one another.
The slit can be in a direction transverse to a length of the bag. Alternatively, the slit can be in a direction parallel to the length of the bag. Regardless of the slit orientation, in some preferred embodiments the flaps may not overlap one another; in other preferred embodiments, the flaps overlap one another.
In one preferred embodiment, each side of the bags has eight contiguous plies with all eight contiguous plies being sealed to one another. In this embodiment, the flaps preferably overlap one another. Preferably, the plastic bags are folded so that they have a total of eight plies on each side of the bag, and preferably, all eight plies are sealed to one another.
In an alternative preferred embodiment, the bags have four contiguous plies sealed together, with flaps not sealed to a remainder of the bag. In this alternative embodiment, the flaps preferably overlap one another.
Although the bag may be made from a monolayer film or a multilayer film, preferably the bag is made from a monolayer film. Although any thermoplastic, film-forming polymer may be used for the bag, preferred polymers include polypropylene, polyethylene homopolymer, polyethylene copolymer, polystyrene, polyamide, and polyester. More preferably, the bags comprise high density polyethylene (HDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), very low density polyethylene (VLDPE), and single site catalyzed polymers (preferably linear homogeneous ethylene/alpha-olefin copolymer or substantially linear homogeneous ethylene/alpha-olefin copolymer having long chain branching). Preferably, the bags are made from a 100% HDPE. Other preferred polymers include polypropylene, low density polyethylene, linear low density polyethylene, very low density polyethylene, and single site catalyzed (preferably linear homogeneous ethylene/alpha-olefin copolymer or substantially linear homogeneous ethylene/alpha-olefin copolymer having long chain branching. Preferred polymer blends include blends of HDPE with LLDPE (5-20 weight percent) and HDPE with LDPE (5-20 weight percent). HDPE is the preferred polymer for use in making the bag film.
Preferably, the film from which the bag is made is a monolayer film. Preferably, the film has a thickness of from 0.1 to 3; more preferably, 0.2 to 1.5 mils; and still more preferably, about 0.3 mil.
The bag in the open position, i.e., when in use, may vary in lay-flat width but is about 14 inches wide lay-flat. Preferably, the bags on the roll are folded so that they each have a width of from about 1 to 7 inches; more preferably, from about 3 to 6 inches; still more preferably, from about 3 to 5 inches; yet still more preferably, about 33/4 inches. Preferably, the axle is at about 1xc2xd inches longer than the width of the roll.
Preferably, the roll of plastic bags is on an axle. Although the axle can be solid or hollow, preferably the axle is hollow. Preferably, the axle is longer than the roll is wide. Preferably, the core has a width of from about 2 inches to about 8 inches; more preferably, from about 4 to 6 inches; still more preferably, from about 4 to 5xc2xd; yet still more preferably, about 5xc2xc inches. Preferably, the axle is at about 1xc2xd inches longer than the width of the roll. Alternatively, the roll of bags can be coreless, with either a hollow center or as a cylindrical roll without a hollow center.
Preferably, the film is corona treated, at least in the area to be printed, as the corona treatment enhances film-to-ink adhesion. In addition, corona treatment imparts a static charge to the bags, increasing bag-to-roll cling, which can be advantageous for the roll of interleaved bags. Finally, corona treatment can make the bag easier to open, in that interply fusion is produced at the open end of the bag by the perforation and slitting. It has been found that the application of corona treatment to the film before slitting and perforating diminishes the fusion from the perforation and slitting, resulting in a bag which is easier to open.
Preferably, the bags have printing on an outside surface thereof, and preferably the printing is confined to a central region on one or both outside plies, with no printing along edge regions with contact the brake plates. More preferably, the printing is confined to the outside surface most visible to the consumer as the bag is being dispensed.
Preferably, the dispenser comprises a brake plate disposed for contact with an outer surface of the roll of bags, the brake being positioned at an acute angle to the direction of translational movement of the core for at least a portion of the translational movement of the core while the core is within the guide channels. Preferably, the brake is present in the form of a pair of narrow brake plates which are positioned to contact outer edges of the roll of bags. Preferably, the brake plates have the same width. Preferably, the brake plates together contact from about 1 to 40 percent of the width of the bag roll; more preferably, from about 5 to 30 percent; still more preferably, from about 10 to 25 percent. Preferably, the dispenser provides a brake point which changes as the roll is depleted.
Preferably, each of the guide channels in the dispenser has an open top and a closed bottom. Preferably, at least a portion of the dispenser is made from wire; preferably, the wire comprises stainless steel. Preferably, the dispenser further comprises a pair of axle constraining members which are spaced wider apart from each other at the open ends of the guide channels than at the closed ends of the guide channels.
As a second aspect, the present invention is directed to a roll of bags for use with a dispenser which dispenses and separates a plastic bag from a roll of plastic bags. The dispenser has a support member for attachment to a support surface and a pair of guide channels carried by the support member for rotatably supporting the roll of plastic bags, a surface which is engageable by the roll of bags when the roll of bags is supported in the guide channels. The improvement comprises a roll of plastic bags wound on the axle, the plastic bags being in the form of a flattened tubular member having at least four contiguous plies, the roll being rotatable with the axle, the axle being axially longer than the roll is wide, with the ends of the axle projecting beyond the ends of the roll a distance sufficient to enable the axle to be supported for rotational and translational movement in the guide channels in such a way that the roll of bags frictionally engages the dispenser at a braking point on the dispenser. The bags are present in the form of a continuous chain of folded, lay-flat, end-seal bags separated by a separation line including a substantially centrally-positioned slit. The bags comprise: (A) first, second, and third longitudinal folds which form a first gusset; (B) fourth, fifth and sixth longitudinal folds which form a second gusset; (C) a seventh longitudinal fold which is on a side of the bag containing the first, second, and third folds, the seventh fold forming a first folded bag flap; (D) an eighth longitudinal fold which is on a side of the bag containing the fourth, fifth, and sixth folds, the eighth fold forming a second folded bag flap. The folds result in each bag being folded into a total of at least eight contiguous plies. The folding and cutting are carried out so that each bag has a total of at least eight contiguous plies, with the slit being through all of the plies, or through less than all of the plies. When a continuous web of such bags are rolled up to form a roll of bags, although either side of the continuous web of folded bags can face outward on the roll, preferably the web is rolled up with the flaps positioned beneath the remainder of the bag, i.e., the flaps being closer to the center of the roll, i.e., facing inward, rather than being present on the outside of the roll. In this manner, the flaps are xe2x80x9ccontainedxe2x80x9d within the roll by the remainder of the bag. However, if the flaps overlap one another, preferably the flaps should be facing outward, exposing the slit below for the tongue to directly engage, i.e., without having the overlapping flaps blocking the tongue from penetration of the slit.